Features of the System Object Model(OD Cookbook)

Inside Macintosh: OpenDoc Cookbook / Part - Appendixes: Appendix B - System Object Model

Features of the System Object Model
SOMobjects(TM) for the Mac OS is the Mac OS implementation of the System Object Model (SOM). It underlies the Mac OS implementation of OpenDoc. SOMobjects for the Mac OS comprises several components, the most important of which are

a kernel, which implements the basic SOM runtime environment
SOM class libraries, which augment the runtime environment
the SOM compiler, which translates SOM's Interface Definition Language (IDL) object specifications into a target language such as C++

SOM is not a complete implementation language or programming system. Instead, SOM complements such languages, providing a number of advantages, such as

language neutrality, so that objects can be implemented in different programming languages yet work together
binary compatibility, solving the "fragile base-class problem," which requires client programs to be recompiled whenever the class library on which they depend is modified
cross-platform compatibility, because SOM is an emerging industry standard implemented on most major platforms

By virtue of these features, SOM enables greater code reuse for object libraries such as OpenDoc and greater flexibility for application programmers.